The present invention relates generally to an indoor air quality module that deactivates an ultraviolet light source if the module is being serviced or if the internal components are installed incorrectly or not installed.
Indoor air can include trace amounts of contaminants, including biospecies, dust, particles, odors, carbon monoxide, ozone, and volatile organic compounds (VOCs) such as formaldehyde, acetaldehyde, toluene, propanol, butene, etc. Indoor air quality modules are used to purify the air by destroying contaminants. The module includes a titanium dioxide coated monolith, such as a honeycomb, and an ultraviolet light source.
Titanium dioxide operates as a photocatalyst to destroy contaminants when illuminated with ultraviolet light. Photons of the ultraviolet light are absorbed by the titanium dioxide, promoting an electron from the valence band to the conduction band, thus producing a hole in the valence band and adding an electron in the conduction band. The promoted electron reacts with oxygen, and the hole remaining in the valence band reacts with water, forming reactive hydroxyl radicals. When contaminants in the air flow through the honeycomb and are adsorbed onto the titanium dioxide coating, the hydroxyl radicals attack and oxidize the contaminants to water, carbon dioxide, and other substances. The ultraviolet light also irradiates and kills the biospecies in the airflow.
If the honeycombs or an air filter are incorrectly installed or not installed in the module, ultraviolet light can leak from the module. Additionally, ultraviolet light can irradiate into the surrounding area during servicing of the module. Ultraviolet light may have several negative effects. For one, it may be harmful to the skin and to the eyes in high doses. Additionally, if ultraviolet light leaks from the module, less ultraviolet light is directed toward the titanium dioxide coating, reducing the number of hydroxyl radials and the photocatalytic effect of the titanium dioxide coating.
Hence, there is a need for an indoor air quality module that deactivates the ultraviolet light source if the module is being serviced or if the internal components are installed incorrectly or not installed.